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A GPS Chip Made to Sip Power, Not Guzzle

SiRF Technology recently announced the development of SiRFstarIV, which sounds like a TV show about a team of teenage spies operating from a groovy beach house.

Courtesy of SiRFstarIV

It is a breakthrough in GPS chip design, which the company says is more accurate than current chips while using 1 percent of the energy. That matters because always-on GPS functions in phones guzzle battery power. This new chip would allow for constant positioning –- and use of location service apps –- while gently sipping electricity.

GPS positioning sucks energy in a two-step process. First, the phone connects to a satellite and locates you. That takes about one second and burns a modest amount of power.

But you still need to know where the satellite is to fix your position. Downloading the satellite’s position takes about 30 seconds and burns lots of power, said Kanwar Chadha, co-founder of SiRF and its vice president for marketing.

Because we know the path of a satellite’s orbit, the chips don’t have to make that 30 second download every time. It’s movements are predictable even if yours are not. The chip can predict a satellite’s position accurately for an hour or two after a getting a good fix. The problem is that doing those calculations also drains battery power.

The new chip, said Mr. Chadha, uses much less power to make those calculations, and can predict a satellite’s position for two to seven days.

Acquiring the satellites is not the only battery drain, though. The GPS receiver uses lots of power to overcome interference from a phone’s other radio signals like Bluetooth, Wi-Fi, and the phone’s microprocessor, to name a few.

The new chip, instead of overcoming those signals, uses a computer program to cancel them out, requiring less power, Mr. Chadha said. It’s like noise-canceling headphones, but for radio signals.

The final enhancement, Mr. Chadha said, is meant to improve the accuracy in urban canyons, indoors, and even deep in tunnels. SiRF’s new software uses a phone’s compass and accelerometers as well as other radio signals to figure the phone’s position, even when it can’t get a signal. “We have the algorithms to do it, but they are not in the market yet,” Mr. Chadha said.

In fact, SiRFstarIV chips won’t show up in consumer devices until next year, Mr. Chadha said, and the dead reckoning software will most likely come later in the year, he said.

Most consumers will not know which new smartphone has one of the energy-conscious SiRF chips. The carriers don’t tend to advertise the names of component makers inside a phone. But consumers are increasingly focused on battery life when they buy new phones, and this chip, if it works as advertised, will help make each charge last longer.

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